Sec Form 4 Filing - Hoge Elizabeth @ Cartesian Therapeutics, Inc. - 2024-10-11

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Hoge Elizabeth 2. Issuer Name and Ticker or Trading Symbol Cartesian Therapeutics, Inc. [ RNAC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O CARTESIAN THERAPEUTICS, INC., 704 QUINCE ORCHARD ROAD 3. Date of Earliest Transaction (MM/DD/YY) 10/11/2024 (Street) GAITHERSBURG, MD20878 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 10/11/2024 M 1,518,373 A 4,555,260 I as trustee ( 2 ) Common Stock 506,377 I by spouse

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series A Non-Voting Convertible Preferred Stock ( 1 ) 10/11/2024 M 45,551.19 ( 1 ) ( 1 ) Common Stock 1,518,373 ( 3 ) 56,402.254 I as trustee ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Hoge Elizabeth C/O CARTESIAN THERAPEUTICS, INC. 704 QUINCE ORCHARD ROAD GAITHERSBURG, MD20878 X Seven One Eight Three Four Irrevocable Trust C/O CARTESIAN THERAPEUTICS, INC. 704 QUINCE ORCHARD ROAD GAITHERSBURG, MD20878 X Signatures /s/ Murat Kalayoglu, Authorized Person 10/15/2024 Signature of Reporting Person Date /s/ Murat Kalayoglu, Authorized Person 10/15/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On October 11, 2024, Seven One Eight Three Four Irrevocable Trust (the "Trust") elected to convert a portion of its shares of the issuer's Series A Non-Voting Convertible Preferred Stock into shares of the issuer's common stock. The remaining shares of the issuer's Series A Non-Voting Convertible Preferred Stock held by the Trust are subject to a beneficial ownership limitation. ( 2 )Shares are held by the Trust. The reporting person is a trustee of the Trust. ( 3 )On November 13, 2023, the issuer acquired the private Delaware corporation which was then known as Cartesian Therapeutics, Inc. in accordance with the terms of an Agreement and Plan of Merger, dated November 13, 2023 (the "Merger"). These securities represent merger consideration payable as a result of the closing of the Merger and securities purchased in a private placement in November 2023.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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